1. Field of the Invention
The present invention relates to an apparatus for adjusting an alignment of optical fibers constituting optical fiber ribbons, which is useful in the fusion splicing of the optical fibers for example.
2. Description of the Background Art
Conventionally, in the collective fusion splicing of the optical fibers constituting the optical fiber ribbon, the alignment of the core axes of the optical fibers to be fusion spliced has been achieved by mounting the optical fibers to be fusion spliced on V-grooves for fixedly mounting the optical fibers which are precisely machined along a straight line so as to be able to align the cladding axes of the optical fibers to be fusion spliced, and then by utilizing the self-alignment effect of the optical fibers due to the surface tension exerted on the optical fibers during the discharge heating process.
However, this surface tension is not quite sufficient to reduce the connection loss significantly, and there still remains a need for adjusting the alignment of each optical fiber.
For this purpose, there has been an apparatus for adjusting the alignment of each optical fiber in the optical fiber ribbon individually, as disclosed in Japanese Patent Application Laid Open No. 5-273430 (1993) which has a configuration as shown in FIG. 1.
In this apparatus of FIG. 1, for each optical fiber 101, there is provided a pair of movable members 102A and 102B having approximately 45.degree. inclined end faces to form a V-groove for mounting each optical fiber 101, each of which is supported by a stationary fixed guide member 100 to be minutely movable up or down, and moved up or down by a stack type piezoelectric element. The position of the optical fiber 101 is adjusted in a desired direction by the appropriate combination of the up and down minute movements of these movable members 102A and 102B so as to adjust the alignment of the optical fibers.
In this conventional apparatus of FIG. 1, in a ease of dealing with the SM (single-mode) type optical fiber which has an outer diameter equal to 125 .mu.m, considering the thickness of a part of the guide member 100 to be provided between the pair of the movable members 102A and 102B, it is necessary for each of the movable members 102A and 102B to have a thickness not greater than 100 .mu.m, but in practice, it is quite difficult to improve the manufacturing precision for the thickness in an order of tens of .mu.m, and the movable member can be damaged very easily. In addition, such thin movable members can be bent very easily, so that the operation to assemble these movable members into a form shown in FIG. 1 has been rather difficult.
On the other hand, there has also been a proposition for the apparatus for adjusting the alignment of each optical fiber in the optical fiber ribbon individually as disclosed in Japanese Patent Application No. H3-280710 (1991), which is suitable for the optical fiber ribbon with a narrow pitch interval between adjacent optical fibers. In this apparatus, in a ease of dealing with the SM type optical fiber having an outer diameter equal to 125 .mu.m, the movable member for pressing the optical fiber is required to have a thickness of about 180 .mu.m, so that the manufacturing of the end face of the movable member is easier and the problem of damaging or the difficulty in assembling can also be reduced compared with the apparatus of FIG. 1.
However, in this apparatus disclosed in Japanese Patent Application No. H3-280710 (1991), the adjacent movable members slide with respect to each other while keeping mutual surface contact, so that there has been a problem that the minute movement of one movable member can be propagated to the neighboring movable members and as a result the already adjusted position of the other optical fiber can be displaced during the adjustment of one optical fiber.